1. Field of the Invention
The present invention generally relates to the field of radio communications networks planning, particularly to the planning of cellular mobile radio communications networks like for example GSM (Global System for Mobile communications) networks and UMTS (Universal Mobile Telecommunications System) networks.
2. Description of the Related Art
As known, a cellular mobile radio communications network includes a plurality of antennas or radio base stations, each one providing radio communications coverage in a respective geographic area, referred to as a cell.
Deploying a cellular mobile radio communications network includes planning the location, the configuration and the radio communications resources (e.g., GSM radio carriers) to be allocated to the different radio base stations.
An aim of the network designers is to ensure that the network being planned provides good coverage of an area of interest. Another aim is to ensure that each radio base station has sufficient radio resources to serve all the traffic that is expected to be generated by the users' mobile communications terminals located in the respective cell (so as for example to minimize blocked calls and dropped calls), without however wasting precious radio resources.
Thus, an aspect of the network planning concerns the estimation of the radio electric coverage of a geographic area of interest by the radio base stations. In this phase, according to the prior art, the area of interest is subdivided into relatively small elementary areas, also referred to as “pixels”, and, using suitable simulation algorithms (such as for example those described in the International published applications WO 2005/076645 and WO 2005/076646, both in the name of the present Applicant), the distribution of the electromagnetic field irradiated by the different radio base stations is calculated; then, best server maps are determined, which provide, for each radio base station, an indication of the area (set of pixels) wherein that radio base station is expected to best serve mobile communications terminals located therein.
The radio electric coverage is for example exploited in other phases of the planning process, such as in the estimation of the distribution of the network traffic in the geographic area intended to be covered by the network under planning (which may be a new area of coverage of a mobile cellular radio communications network, or an already deployed network area, which needs to be updated). A correct forecast of the traffic distribution is indeed essential for a proper dimensioning of the radio resources of the different cells of a network area to be planned, and thus to the capability of satisfying the requests by the users, thereby providing a highly satisfactory service thereto.
As described for example in U.S. Pat. No. 6,097,959, conventional radiotelephone service planning systems and methods generate the best server images based primarily on estimated pathloss, i.e. using signal strength levels at specific locations.
In other words, the generic pixel of the area of interest is assigned to a certain radio base station based which, compared to the other radio base stations, produces the highest signal strength level on that pixel.